The present invention relates generally to a disk apparatus, and more particularly to an optical disk storage in which a movable part having an optical head moves along a guide shaft in a radial direction of an optical disk.
The following is a description of the configuration of a movable part and guide shafts in a conventional optical disk apparatus.
In one conventional optical disk apparatus, as shown in FIGS. 1A and 1B, a pair of parallel guide shafts 3a and 3b are fixed on a frame which defines a apparatus body, and a movable part 2 having an optical head 1 is located between the shafts 3a and 3b. These guide shafts 3a and 3b are engageable with the movable part 2 and extend parallel to a radial direction of an optical disk (not shown). As the movable part 2 moves along the guide shafts 3a and 3b, the optical head 1 can move in the radial direction of the optical disk to record information thereon and/or reproduce information therefrom. The movable part 2 has a flat hexagonal section shown in FIG. 1B, and includes six rollers 4a to 4f, a flat plate 5, and a compression spring 6. Four rollers 4c to 4f touch the guide shaft 3a whereas two rollers 4a and 4b touch the guide shaft 3b, the roller 4a being fixed on the flat plate 5. One end of the flat plate 5 is screwed into the movable part 2, and the other end thereof is compressed by the compression spring 6. The roller 4a is thus compressed toward the guide shaft 3b, and the other rollers 4b to 4f are reactively compressed toward the guide shafts 3a and 3b. Since all the rollers 4a to 4f are compressed toward the guide shafts 3a and 3b, the movable part 2 is supported between the shafts 3a and 3b.
In another conventional optical disk apparatus, as shown in FIGS. 2A and 2B, only the guide shaft 3a is fixed on the frame. The movable part 2 includes three rollers 7a to 7c, the rollers 7a and 7b being engaged with the guide shaft 3a, and the roller 7c being engaged with the guide shaft 3b. The guide shaft 3b is compressed toward the roller 7c by a flat spring 8 which is fixed on the frame and extends parallel to the guide shaft 3b. Thus, the rollers 7a and 7b are compressed toward the guide shaft 3a, and the movable part 2 is supported therebetween.
However, the above conventional optical disk apparatuses have the following disadvantages. In the former optical disk apparatus, the movable part 2 includes the compression spring 6, and thus cannot be made small. In addition, although the rollers 4a to 4f must be engaged with the guide shafts 3a and 3b via a desired compression force in order that the movable part 2 can move smoothly and stably along the guide shafts 3a and 3b, it is difficult to obtain the desired compression force since the compression force of the compression spring 6 cannot be adjusted. The latter optical disk apparatus can be made smaller than the former, but since the flat spring 8 comprises a flat plate such that it can easily be deformed, it is difficult to uniformly distribute the compression force thereof along the guide shaft 3b. Due to deviation of the compression force of the flat spring 8, the optical head 1 deviates from a desired position as the movable part 2 moves, hence it cannot properly perform recording/reproducing operations. In addition, the compression force of the flat spring 8 cannot be adjusted.